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Encyclopedia > Craton
World geologic provinces. (USGS) Oceanic crust ██ 0-20 Ma ██ 20-65 Ma ██ >65 Ma Geologic province ██ Shield ██ Platform ██ Orogen ██ Basin ██ Large igneous province ██ Extended crust
World geologic provinces. (USGS)
Oceanic crust ██ 0-20 Ma ██ 20-65 Ma ██ >65 Ma Geologic province ██ Shield ██ Platform ██ Orogen ██ Basin ██ Large igneous province ██ Extended crust

A craton (kratos; Greek for strength) is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Cratons are generally found in the interiors of continents and are formed of a crust of lightweight felsic igneous rock such as granite attached to a section of the upper mantle. A craton may extend to depth of 200 km. Image File history File links Download high resolution version (1200x637, 114 KB) Map of world geologic provinces. ... Image File history File links Download high resolution version (1200x637, 114 KB) Map of world geologic provinces. ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In geology, a supercontinent is a land mass comprising more than one continental core, or craton. ... Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Earth cutaway from core to exosphere. ...


Cratons are subdivided geographically into geologic provinces, each province being classified as an Archon, a Proton or a Tecton according to its age: A geologic province is a spatial entity with common geologic attributes. ...

  • Archons: consist of rocks from the Archaean era, older than 2.5 billion years (2.5 Ga).
  • Protons: consist of rocks from the early to middle Proterozoic era, older than 1.6 Ga.
  • Tectons: consist of rocks from the late Proterozoic era, with ages between 1.6 Ga and 800 million years (800 Ma).

As minerals (such as precious metals and diamonds) in the Earth's crust tend to become separated with time, the oldest cratons are of the greatest interest to mining companies. Cratons are still being defined by ongoing geological and geophysical research. The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... In geology, the Proterozoic is an eon before the first abundant complex life on Earth. ... In geology, the Proterozoic is an eon before the first abundant complex life on Earth. ... A gold nugget A precious metal is a rare metallic chemical element of high economic value. ... // For other uses, including the shape ◊, see Diamond (disambiguation). ... The Blue Marble: The famous photo of the Earth taken en route to the Moon by Apollo 17s Harrison Schmitt on December 7, 1972. ... ‹ The template below has been proposed for deletion. ...

Contents

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Craton formation

The process by which cratons are formed from early rock is called cratonization. The first large cratonic landmasses formed during the Archean eon. During the Early Archean the Earth's heat flow was nearly three times higher than it is today because of the greater concentration of radioactive isotopes and the residual heat from the Earth's accretion. Tectonic and volcanic activity were considerably more active than they are today; the mantle was much more fluid and the crust much thinner. This resulted in rapid formation of oceanic crust at ridges and hot spots, and rapid recycling of oceanic crust at subduction zones. The Earth's surface was probably broken up into many small plates with volcanic islands and arcs in great abundance. Small protocontinents (cratons) formed as crustal rock was melted and remelted by hot spots and recycled in subduction zones. The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... Accretion, means any growth or increase in size by a gradual external addition or inclusion. ... ... This article is about volcanoes in geology. ... Earth cutaway from core to exosphere. ... Age of oceanic crust Oceanic crust is the part of Earths lithosphere which underlies the ocean basins. ... In geology, a hotspot is a location on the Earths surface that has experienced active volcanism for a long period of time. ... Subduction zones mark sites of convective downwelling of the Earths lithosphere. ...


There were no large continents in the Early Archean, and small protocontinents were probably the norm in the Mesoarchean because they were probably prevented from coalescing into larger units by the high rate of geologic activity. These felsic protocontinents (cratons) probably formed at hot spots from a variety of sources: mafic magma melting more felsic rocks, partial melting of mafic rock, and from the metamorphic alteration of felsic sedimentary rocks. Although the first continents formed during the Archean, rock of this age makes up only 7% of the world's current cratons; even allowing for erosion and destruction of past formations, evidence suggests that only 5-40% of the present continental crust formed during the Archean. (Stanley, 1999). Felsic is a term used in geology to refer to silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silica, oxygen, aluminium, sodium, and potassium. ... The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ...


A technical but very succulent evolutionary perspective of how the cratonization process probably first began in the Archean is given by Hamilton (1999):

Very thick sections of mostly submarine mafic, and subordinate ultramafic, volcanic rocks, and mostly younger subaerial and submarine felsic volcanic rocks and sediments were oppressed into complex synforms between rising young domiform felsic batholiths mobilized by hydrous partial melting in the lower crust. Upper-crust granite-and-greenstone terrains underwent moderate regional shortening, decoupled from the lower crust, during compositional inversion accompanying doming, but cratonization soon followed. Tonalitic basement is preserved beneath some greenstone sections but supracrustal rocks commonly give way downward to correlative or younger plutonic rocks... [Mantle] plumes probably did not yet exist, and developing continents were concentrated in cool regions. Hot-region upper mantle was partly molten, and voluminous magmas, mostly ultramafic, erupted through many ephemeral submarine vents and rifts focussed at the thinnest crust.... Surviving Archean crust is from regions of cooler, and more depleted, mantle, wherein greater stability permitted uncommonly thick volcanic accumulations from which voluminous partial-melt, low-density felsic rocks could be generated.

Editorial note: The process of craton formation is extremely contentious. The paper by Hamilton (1999) is, if anything, even more contentious, and represents a minority view that is not generally endorsed by the geological community. An even-handed summary of the leading theories of craton formation (thrust stacking vs deep mantle melting events) is required here - and this is not one of them. Furthermore, I wonder if "succulent" is an appropriate descriptive term for scientific writing. 137.111.13.34 03:38, 13 October 2006 (UTC)Dr C. O'Neill, Geodynamicist, Macquarie University

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Named cratons

Listed by modern continent, include:

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Africa

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The Congo craton, covered by the Palaeozoic-to-recent Congo basin, is an ancient Precambrian craton that with four others (the Kaapvaal, Zimbabwe, Tazania, and West African cratons) makes up the modern continent of Africa. ... The Bangweulu Block is a cratonic unit that forms part of the Congo craton of central Africa. ... The Kaapvaal craton (Kaapvaal province of South Africa), along with the Pilbara craton of Western Australia, are the only remaining areas of pristine 3. ... The Kalahari craton occupies a large portion of South Africa and consists of the Kaapvaal, the Zimbabwe craton, the Limpopo belt, and the Namaqua Belt. ... The Zimbabwe craton is an example of Early Archaean lithology dating back to 3. ...

Antarctica

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East Antarctica with Australia (top) during the early Paleozoic The East Antarctic craton is an ancient craton that forms most of Antarctica. ...

Australia

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Basic geological regions of Australia, by age. ... The Pilbara craton (the Pilbara province in northwest Western Australia), along with the Kaapvaal craton (the Kaapvaal province of South Africa) are the only remaining areas of pristine Archaean 3. ... The Yilgarn Craton is a craton which constitutes the bulk of the Western Australian land mass. ...

Eurasia

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The Dharwar craton in South India presents a natural cross-section of late-Archaean continental crust. ... The North China Craton is one of the smaller continental cratons of the Earth. ... In geology and tectonics, the Sarmatian craton is the southern segment/region of the East European craton. ... For other meanings of the word Volga see Volga (disambiguation) Волга Length 3,690 km Elevation of the source 225 m Average discharge  ? m³/s Area watershed 1. ... The Ural Mountains, (Russian: Ура́льские го́ры = Ура́л) also known simply as the Urals, are a mountain range that run roughly north and south through western Russia. ... Siberian Federal District (dark red) and the broadest definition of Siberia (red) Siberia (Russian: , Sibir’; Tatar: Seber) is a vast region of Russia and northern Kazakhstan constituting almost all of Northern Asia. ...

North America

North American cratons and basement rocks.
North American cratons and basement rocks.
North American craton ██ North American craton ██ Deformed craton ██ Accretionary belt
North American craton ██ North American craton ██ Deformed craton ██ Accretionary belt
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North American cratons and basement rocks. ... North American cratons and basement rocks. ... World map showing North America A satellite composite image of North America. ... Image File history File links North_america_craton_nps. ... Image File history File links North_america_craton_nps. ... The North American craton, like all craton land, was created as continents move about the surface of the Earth, bumping into other continents and drifting away. ... Canadian Shield The Canadian Shield is a large craton in eastern and central Canada and adjacent portions of the United States, composed of bare rock dating to the Precambrian Era (between 4. ... North America cratons and basement rock. ... Guiana (also known as the Guiana highlands or the Guiana shield) forms a portion of the northern coast of South America. ... The North American craton, like all craton land, was created as continents move about the surface of the Earth, bumping into other continents and drifting away. ... North America cratons and basement rock. ... North America cratons and basement rock. ... The Northwest Territory, also known as the Old Northwest and the Territory North West of the Ohio, was a government and region within the early United States. ... North America cratons and basement rock. ... This article does not cite its references or sources. ...

Northern and Eastern Europe

    • East European craton
    • Belomorian craton, part of the Fennoscandian Shield, between the Karelian and Kola cratons
    • Baltic Shield, part of the East European craton
    • Fennoscandian Shield, the exposed Northwestern part of the Baltic Shield in Norway, Sweden and Finland (3.1 Ga)
    • Karelian craton, part of the Fennoscandian Shield in Southeast Finland and Karelia Russia, (3.4 Ga)
    • Kola craton, part of the Fennoscandian Shield, Kola Peninsula, Northwest Russia
    • Midland craton of England and Wales
    • North Atlantic Craton
    • Ukrainian Shield
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The East European craton is the core of the Baltica proto-plate and consists of three crustal regions/segments: Fennoscandia to the northwest, Volgo-Uralia to the east, and Sarmatia to the south. ... The Baltic Shield (or Fennoscandian Shield) is a segment of the Earths crust belonging to the East European Craton, representing a large part of Fennoscandia, northwestern Russia and the northern Baltic Sea. ... The Baltic Shield (or Fennoscandian Shield) is a segment of the Earths crust belonging to the East European Craton, representing a large part of Scandinavia, northwestern Russia and the northern Baltic Sea. ... Map showing the parts Karelia is traditionally divided into. ... Location of Kola south of the Barents Sea. ... Motto: (French for God and my right) Anthem: Multiple unofficial anthems Capital London Largest city London Official language(s) English (de facto) Government Constitutional monarchy  - Queen Queen Elizabeth II  - Prime Minister Tony Blair MP Unification    - by Athelstan AD 927  Area    - Total 130,395 km² (1st in UK)   50,346 sq... Motto: (Welsh for Wales for ever) Anthem: Hen Wlad Fy Nhadau Capital Cardiff Largest city Cardiff Official language(s) English, Welsh Government Constitutional monarchy  - Queen Queen Elizabeth II  - Prime Minister Tony Blair MP  - First Minister Rhodri Morgan AM Unification    - by Gruffudd ap Llywelyn 1056  Area    - Total 20,779 km² (3rd...

South America

    • Amazonian craton
    • Rio de la Plata craton
    • San Francisco craton
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Amazonian redirects here, for other uses see Amazonian (disambiguation) The Amazon Basin is the part of South America drained by the Amazon River and its tributaries. ...

References

  • Dayton, Gene. (2006) "Geological Evolution of Australia." Sr. Lecturer, Geography, School of Humanities, Central Queensland University, Australia.[1]
  • Hamilton, Warren B. (1999) "How did the Archean Earth Lose Heat?." Department of Geophysics, Colorado School of Mines, Journal of Conference Abstracts, Vol. 4, No. 1, Symposium A08, Early Evolution of the Continental Crust.[2]
  • Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0716728826 p. 297-302

  Results from FactBites:
 
Craton - Wikipedia, the free encyclopedia (234 words)
A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years.
Cratons are generally found in the interiors of continents and are formed of a crust of lightweight felsic igneous rock such as granite attached to a section of the upper mantle.
Cratons are subdivided geographically into geologic provinces, each province being classified as an Archon, a Proton or a Tecton according to its age:
North American craton - Wikipedia, the free encyclopedia (334 words)
While much of the stable craton is exposed at the surface north of Indiana as the Canadian Shield, the middle of the craton, located in the United States, is covered with sedimentary rocks of the Interior Platform.
The cratonic rocks are metamorphic and igneous while the overlying sedimentary rocks are composed mostly of limestones, sandstones, and shales.
Much of this time the craton was covered by a large shallow sea, a so-called "epicratonic sea" (meaning literally "on" the craton).
  More results at FactBites »

 
 

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